Relationship between chronic obstructive pulmonary disease and levels of vitamin D

Abstract

Objective: Vitamin D deficiency may be associated with pulmonary function deterioration. The aim of this study is to assess the relationship of serum vitamin D levels with pulmonary functions, disease severity and exacerbation frequency in Chronic Obstructive Pulmonary Disease (COPD) patients. Methods: Seventy consecutive patients with COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II-IV) who presented to our outpatient clinic and thirdty controls entered to the study. Diagnosis of COPD was confirmed according to clinical findings and pulmonary function test. Serum 25-hydroxyvitamin D (25(OH)D levels were measured by immunofluorescence method. Levels <20 ng/mL defined deficiency. Associations between Vitamin D levels and sex, age, body mass index (BMI), smoking habit, comorbidities, exacerbation frequency were examined. Results: The mean age of patients was 60.7 years. The proportion of patients in stages 2 of GOLD was 40 %, in stages 3 was 30 % and stages 4was 30 %. There was no significant difference in serum levels of 25(OH)D between COPD patients and controls. Vitamin D level was 9.3 ±6.0 ng/mL in control group and 9.7± 8.5 ng/mL in GOLD stage 2, 9.6 ± 6.2 ng/mL in stage 3 and 5.1 ±2.4 ng/mL in stage 4. In stage 4, vitamin D levels was significantly lower statistically (p=0.03). Among the COPD patients, lower FEV1 was associated with lower levels of 25(OH)D (p= 0.03). The most frequent comorbidities were hypertension (61.4%) and heart failure (27.1%). Among the COPD patients smoking associated with significantly lower levels of serum 25(OH) D (p=0.04). We find an association with exacerbation frequency in the previous 12 months and levels of 25(OH) D (p=0.02). Conclusion: COPD severity according to GOLD stage is also associated with low levels of 25(OH)D. Serum vitamin D levels are lower in COPD patients who are current smokers. Severe vitamin D deficiency is related to more frequent disease exacerbations. These findings indicated a relationship between serum 25(OH)D concentrations and COPD which suggests optimization of serum vitamin D levels in COPD. Key words: Pulmonary functions, Vitamin D, COPD